Idle vent valve



Sept. 9, 1958 E. OLSON 2,851,259

IDLE VENT VALVE Filed April 23, 1956 INVENTOR ELMER OLSON BY QQ%QW\ ATTORNEY United States Patent IDLE VENT VALVE Elmer Olson, Rochester, N. Y., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application April 23, 1956, Serial No. 579,806

3 Claims. (Cl. 261-43) The present invention relates to an improved fuel bowl vent mechanism for a carburetor.

In addition to vents which normally communicate the upper or liquid-free portion of a fuel or float bowl chamber to the induction passages anterior of the choke valve, or which vents otherwise communicate the bowl directly to atmosphere, in order to maintain the bowl at substantially atmospheric pressure, it has also been found desirable to provide a throttle controlled valve which vents such bowl, particularly the bowl supplying the primary induction passages in a compound or four barrel type carburetor, when the throttle is in a closed or near closed position. This basic arrangement is shown in copending application Serial No. 264,136 Olson et a1. filed December 29, 1951 now Patent No. 2,771,282 dated November 20, 1956.

Due to other improvements in vehicle design since the inception of the basic vent system referred to above, a need has arisen requiring an improvement in the aforementioned venting system. With improved types of vehicle suspension systems, it is now possible for vehicles to negotiate corners or turns at higher vehicle speeds than ever before. Consequently, the increased centrifugal forces shift the fuel in the fuel bowls and raise the level to a point where, when the throttle is in its closed or near closed position and the throttle controlled vent open, the liquid fuel frequently splashes out of the vent and onto the exterior of the carburetor. Obviously this expelling of fuel is undesirable in terms of the fuel wasted, as well as presenting a possible fire hazard.

It is, therefore, broadly the purpose of the present invention to provide a device which prevents liquid fuel from being splashed or otherwise expelled from a fuel bowl vent.

More specifically, this invention provides a fuel controlled device which will prevent fuel from being splashed out of the throttle controlled vent and which device further cooperates with a throttle controlled valve to permit the fuel bowl to be maintained at substantially atmospheric pressure while precluding the aforenoted uncontrolled expulsion of fuel from the bowl.

The objects and advantages of the present invention will be apparent from a perusal of the detailed description of a preferred form of the device as set forth below and as illustrated in the drawings.

In the drawings:

Figure 1 is a partially sectioned elevational view of a carburetor embodying the subject invention.

Figure 2 is a fragmentary plan view of Figure 1 showin'bg further the venting mechanism.

Figure 3 is an enlarged fragmentary elevational section .showing the subject venting mechanism in detail.

Referring to Figure l, a carburetor is shown generally at and includes a fuel bowl or reservoir casing 12, a throttle body 14 and a reservoir cover 16. Mounted on a shaft 18 in the throttle body is a throttle valve 20, shown in a substantially closed position. Also fixed to the throttle shaft 18 is a lever 22 articulated at one end to a throttle ICC pedal controlled rod 24. Likewise fixed to the throttle shaft 18 and adapted to rotate therewith is another lever 26 to which is articulated one end of a control link 28.

As already referred to above, it has been found desirable to provide a reservoir venting mechanism which opens the reservoir to atmosphere when the throttle valve is in a closed or substantially closed position, the purpose of this type of vent being generally to maintain the float bowl reservoir at atmospheric pressure which facilitates starting a hot engine. To this end, the fuel reservoir cover 16 is provided with an upstanding hollow vent casing 30 which communicates at its lower end with the upper or fuel free portion of the fuel reservoir. The vent casing 30 is formed with horizontally aligned openings 32 and 34 therethrough. Opening 34 has securely fitted therein an apertured cover 36 which is adapted to slidably support a valve member 38. The valve member 38 includes a stem 40 slidably supported in the cover 36 and a valve head 42 adapted to seat against and close opening 32 in the vent casing 30. A seat or retainer member 44 is mounted on the end of valve stem 40 exteriorly of the vent casing 30 and is adapted to support one end of a spring 46, the other end of which spring biases against cover 36 and thereby urges the valve stem and head to the left, as viewed in Figure 1, to close port 32.

In order to open valve 38 by moving valve head 42 away from the vent port 32, a lever 50 is centrally pivotably mounted on the fuel reservoir casing 16 through a stud 51. Lever 50 includes a pair of arms 52 and 54.

The arm 54 is adapted to engage with valve stem 40 and upon rotation of the lever 50 control the movement of vent valve 38. Arm 52 of lever 50 is articulated to the other end of throttle control link 28.

In the vent mechanism as thus far described it will be seen that with the throttle valve 20 closed or substantially closed, the vent valve 38 is held in an open position thereby communicating the fuel reservoir to atmosphere. This will be the condition of the vent mechanism whenever the throttle valve is in an idling position. While this position is most often achieved when the vehicle is at rest, it is also possible for the vent valve 38 to be in identically the same position when the vehicle is negotiating a turn at relatively high speeds and the operator closes the throttle to reduce the engine power output. It is under this latter condition particularly that fluid fuel is frequently expelled through the vent mechanism with the resultant waste and potential fire hazard referred to above. It is to eliminate this loss of fuel through the vent mechanism that the present invention is directed.

It is apparent that the problem of fuel being expelled through the vent mechanism is serious only when the throttle is in its closed or substantially closed position, as shown in Figure 1, since when the throttle valve 20 and shaft 18 are rotated in a clockwise direction to open the throttle, lever 26 is similarly rotated raising link 28 to rotate lever 50 in a counterclockwise direction and moving arm 54 away from the valve stem 40 permitting the spring 46 to close the vent valve 38. In this condition, any fluid fuel impelled toward the venting mechanism is denied egress by the vent valve head 42 which is then seated against the vent port 32.

Thus, in order to prevent fluid fuel from being splashed or otherwise expelled through the vent port 32 when the throttle has opened the vent valve 38, as shown in the drawings, an impact type valve 60 has been mounted in the casing 16 in series with the vent valve 38. More specifically, a valve seat or port 62 is formed at the bottom or lower end of the vent casing 30 in such a way as to be closed under certain conditions by the impact valve 60.

The valve 60 is loosely mounted on a stud 64 which is threaded into the inner surface of the cover 16. In this way, and as particularly seen in Figure 3, impact valve 6.0 will normallyfall open with respect to port or seat 62 under the influence of gravity and will thus permit the fuel reservoir to be communicated to atmosphere, assuming the throttle position so dictates with respect to valve 3.8 as described above. Thus, under normal operatingconditions vent valve 38 is biased closed Whereas impact valve 60 is opened, while during normal venting conditions both valves 38 and 60 are opened permitting communication of the fuel reservoir to atmosphere.

In the eventuality, as suggested above during high speed turning, that vehicle operating conditions are such as to impel fluid fuel in the reservoir out of the vent mechanisrn, valve 60 will close port 62 under the impact of this fuel endeavoring to so escape. After the impact of the impelled fluid fuel has abated, valve 60 will again under the influence of gravity return to its open position permitting normal venting to take place.

It is apparent that valve 60. will only be closed under the impact of the fluid fuel tendingto escape through the venting mechanism whereas fuelvapors which are desirably vented to atmosphere pass around the valve 60 and through the venting mechanism being otherwise unimpeded by said valve.

It is apparent that other structural variations of the subject invention are possible within the scope of the teaching as set forth and described.

I claim:

1. A carburetor venting device comprising a fuel reservoir containing liquid fuel, a throttle valve, a port connecting said reservoir to atmosphere, first valve means cooperating with and normally closing said port, means operatively connecting said throttle valve and said first valve means enabling said valve means to be open when said throttle valve is in a substantially closed position, and second valve means disposed proximate said first valve means, said second valve means being in a normally open position and adapted to be closed by the liquid fuel in said reservoir whereby fuel is prevented from being expelled from said reservoir through said port even when said first valve is opened.

2. A carburetor venting device comprising a throttle valve, a fuel reservoir containing liquid fuel, a pair of series arranged ports adapted to communicate said reservoir to atmosphere, a first valve cooperating with one of said ports, means operatively connecting said throttle valve and said first valve to open the associated port only when said throttle is substantially closed, and an impact valve cooperating with and normally opening the other port, said impact valve being adapted to be closed by contact with the liquid fuel in said reservoir tending to escape through said associated port whereby fuel is prevented from being expelled from the fuel reservoir even when said first valve is opened.

3. A- carburetor including in combination a fuel reservoir containing fluid fuel, a cover for said reservoir, a throttle body, a throttle valve mounted in said body, and a vent mechanism on said cover, said mechanism including first and second ports formed in said cover, said ports being arranged in series a first valve mounted in said cover and biased to normally close said first port, linkage means interconnecting said throttle valve and the first valve for opening the latter when the throttle valve is substantially closed and a second valve loosely mounted on the inside of the cover proximate first port and normally uncovering said second port under the influence of gravity, said second valve being adapted to close its associated port under the impact force of the fluid fuel in said bowl tending to escape through the vent mechanism whereby fuel is prevneted from being expelled from the fuel reservoir even when said first valve is opened.

References Cited in the file of this patent UNITED STATES PATENTS 1,567,807 Mock Dec. 29, 1925 1,916,060 Memini June 27, 1933 2,013,787 Moseley Sept. 10, 1935 2,441,301 Waag et al May 11, 1948 FOREIGN PATENTS 575,659 Great Britain Feb. 27, 1946 

